We report Surface Enhanced Raman Spectroscopy (SERS) measurements on nanostructured gold surfaces prepared using a primary vacuum sputtering technique. Even if no molecules have been deposited on the metallic surface a clear Raman signal is observed. A very intense and sharp peak around 2100 cm-1 together with low frequency modes are visible. The comparison between the experimental spectra and those obtained using Density functional theory (DFT) calculations confirms that these new modes are associated to the cyanide compound Au(CN)2-. This proves the high sensitivity of SERS for the chemical analysis of metallic surfaces. It also shows that the pollution should be carefully taken into account in SERS analysis. We also demonstrate that high power laser illumination transform these toxic compounds into carbon species, this method can be used to clean SERS substrates.

The effects of atmospheric deposition on plankton community structure wereexamined during a mesocosm experiment using water from the Cretan Sea (EasternMediterranean), an area with a high frequency of atmospheric aerosol deposition events.The experiment was carried out under spring-summer conditions (May 2012). Themain objective was to study the changes induced from a single deposition event,on the autotrophic and heterotrophic surface microbial populations, from viruses tozooplankton. To this end, the effects of Saharan dust addition were compared to theeffects ofmixed aerosol deposition on the plankton community over 9 days. The effects ofthe dust addition seemed to propagate throughout the food-web, with changes observedin nearly all of the measured parameters up to copepods. The dust input stimulatedincreased productivity, both bacterial and primary. Picoplankton, both autotrophic andheterotrophic capitalized on the changes in nutrient availability and microzooplanktonabundance also increased due to increased availability of prey. Five days after thesimulated deposition, copepods also responded, with an increase in egg production.The results suggest that nutrients were transported up the food web through autotrophs,which were favored by the Nitrogen supplied through both treatments. Although, theeffects of individual events are generally short lived, increased deposition frequencyand magnitude of events is expected in the area, due to predicted reduction in rainfall and increase in temperature, which can lead to more persistent changes in planktoncommunity structure. Here we demonstrate how a single dust deposition event leadsto enhancement of phytoplankton and microzooplankton and can eventually, throughcopepods, transport more nutrients up the food web in the Eastern Mediterranean Sea.

Heterotrophic bacterial communities in marine environments are exposed to a heterogeneous mixture of dissolved organic compounds with different bioreactivity that may control both their activity and composition. The coastal environment is an example of a mixing area where recalcitrant allochthonous organic matter from rivers can encounter labile organic matter from marine phytoplanktonic blooms. The objective of this study was to explore the effects of mixed qualities of dissolved organic matter (DOM) on bacterial community activity (BCA) and bacterial community composition (BCC) and to test for a priming effect when DOM sources are added in combination. Coastal marine bacterial communities were incubated separately with a mixture of amino acids and with natural riverine DOM or with both sources together for 42 days. Addition of amino acids alone or in combination with riverine DOM led to a similar stimulation of BCA compared to control condition, whereas addition of riverine DOM alone did not modify BCA compared to the control. On the contrary, BCC analyzed by 16S rRNA gene pyrosequencing was not affected by the addition of amino acids alone, but changed dramatically with riverine DOM alone or in combination with amino acids. Our results show that changes in BCA and BCC can be driven by different types of DOM, but that these changes are not necessarily coupled. Moreover, the addition of labile DOM did not modify the microbial decomposition of riverine DOM, nor the BCC, suggesting that a priming effect did not occur under these experimental conditions.